Reset circuit
US4520418A · kind A · utility
Inventor
Key dates
| Filing date | Apr 25, 1983 |
| Grant date | May 28, 1985 |
| Priority date | — |
| Expiry date | Apr 25, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K2017/226
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A reset circuit which monitors the voltage of the power supplied to a microprocessor unit, and produces a low resistance to ground at the reset terminal of the microprocessor whenever the supply voltage changes from a low value to a high value, or from a high value to a low value. It is based upon the combination of two RC circuits of different time constants, such that when the supply voltage is constant, no current flows in these circuits. A transistor is connected to the RC network such that it carries current only when there is a changing voltage of the power supply. If the voltage increases or decreases, a second transistor acting as an electronic switch grounds the reset terminal, and when the voltage becomes constant again, either at a high value or a low value, the switch opens and the reset voltage goes high.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.